In the past, piston paint pumps of the type having a paint pumping piston required periodic lubrication of the paint pumping piston by a user who was instructed (by the owner's manual) to insert a spout of an oil can into an opening in the pump housing and align the spout with the top of the piston where it projected from a nut or bushing supporting the paint pumping piston and retaining the top seal of the paint pumping piston assembly. Such a lubrication procedure was found to be inconvenient and therefore less likely to be performed as often as appropriate. Because the oil was stored in a can separate from the pump, it was also inconvenient for a user to locate the oil can when lubrication was intended to be performed.
The present invention overcomes deficiencies of the prior art by providing an on board lubrication system on the pump. The system includes an oil reservoir and a prepositioned permanently installed spout located to deliver the oil to the piston-bushing interface upon exercise of the system by the user to deliver a predetermined amount of oil to the piston-bushing interface.